Sharif Digital Repository

The main objective of this study is evaluation of several nonlinear observers and comparing their performances.First, the literature review is presented; and then the process model is described. Second, observability and the observer design is disscused. Performances of Lunberger, sliding, and high gain nonlinear observers have been compared. Finally, the performance of a high gain observer in a closed-loop system including the back stepping controller has been evaluated.
 

Anesthesia control during surgeries has been greatly considered in recent years. In this thesis nonlinear and linear control algorithems are implemented to control the human anesthesia system. First, non-adaptive linear model predictive algorithem is tested. Since the model parameters change from one person to another, adaptive algorithms seem more suitable for the system. Therfore, adaptive linear predictive control is implemented in the next step, and it shows a better performance. According to the system nonlinearities, non-adaptive nonlinear model predictive control (NMPC) based on the state-space model is also applied to the system and it has a better performance index. The main problem... 

In this study steady state and dynamic simulation of an NFM extractive distillation unit for seperation of aromatics and non-aromatic components has been carried out. Column output composition obtained with experimental binary coefficients is compared with those obtainded by UNIFAC equation. The results indicate that using UNIFAC for all binrary coefficients results in an unacceptable error in concentration of benzene. If the experimental binary coefficents of benzene with NFM are used and the rest are calculated by UNIFAC equation, the simulation results will be very close to those obtained via experimental binary coefficients. Also it is shown that considering a constant efficiency for all... 

This project presents appropriate strategies for HIV infection treatment. In order to close the presented strategy to real treatment regimen, appropriate parameters are selected for the HIV infection model, real outputs are considered for the system, and three widely used drugs (one PI: ritonavir (RDV), two RTIs: lamivudine (3TC) and zidovudine (ZDV)) are used to design a drug regimen. A Luenberger-like nonlinear observer (LNO) is also designed for estimation of unmeasurable states. In order to minimize the side effects of drug regimen, the concentration of ZDV is fixed at a minimum value at all time because this drug has a greater side effects than other drugs and the parameters of... 

The object of this research is modeling, simulation and control of a crystallization process. Population balance equation (PBE) has been used for modeling of such processes. Most of the existing numerical methods cannot solve the general form of PBE in presence of the breakage and agglomeration terms and some others are not suitable for control objectives, because of their intractable CPU time. In this work a new developed numerical method called conservation element and solution element (CE/SE) has been used for solving general form of multidimensional population balance equations. The accuracy and effectiveness of the scheme is demonstrated through computer simulation. According to the... 

This research is trying to investigate the control algorithms of unknown control direction systems. Since Nussbaum function is the most common method which in used for these systems this research focus on this algorithm to overcome control the effect of unknown control direction. This research study the performance of different control algorithms in controlling such systems followed by analysis of two control modes of continuous and discrete using Nussbam Function. Additionally, in continuous mode, the performance of two methods of backstepping and liding mode has been compared on the given system in variety of situation. Results demonstrate that backstepping method shows better performance... 

Anaerobic digestion is a useful process that is very important, addition to producing methane as energy source, it can be used for treatment of solid waste and sewage sludge. This process due to the presene of chemical and biological reactions and abundant chemical species, is very complicated and sensitive, so it is very unstable against any kind of change. as for the large importance of the process, we need control and optimization. In order to improving the performance of the process and increasing biogas and methane production, we should control and optimize the process. ADM1 is principal and the most accurate model for this process, a variety of reduced order models used to design... 

Selection of the most appropriate control configuration for two point control strategy in a distillation column is a challenging problem. In the present work, three control configurations namely , and , have been employed to control a high purity distillation column separating the binary mixture of Benzene-Toluene. A simple linear model for the process has been derived via a system identification technique. The uncertainty and performance weights have been defined and have been utilized to design a robust controller based on the μ-synthesis approach. The genetic algorithm is employed and the peak value of μ is minimized in order to obtain appropriate PI controller parameters for each... 

Existence of time delay and interactions of control loops make control of multivariable delayed systems more difficult، therefore control of these systems is important. In this project a control scheme based on prediction of process output has been proposed. Traditional PI controllers are used in the control structure and controller parameters are tuned by genetic algorithm. Unlike the Smith predictor based methods، which become internally unstable when applied to unstable plants، unstable delayed multivariable systems can be handled by proposed method. It can also be applied to stochastic systems. The robust version of the control scheme has also been designed. Effectiveness of the proposed... 

In this study, adaptive control of HIV infection was investigated based on feedback linearization. First, three state model of HIV infection was simplified to implement the adaptive approaches by using some assumptions. Then, adaptive control method based on feedback linearization was implemented on reduced order and three states infection dynamic model with including the RTIs and PIs drugs effects as control input. The parameter projection method, adaptive nonlinear observer and dynamic anti-windup were employed in implementation of adaptive control method to prevent singularity problem, to estimate system states and to avoid windup problem of external PID controller, respectively. Finally,... 

In this thesis, a bioreactor with oscillatory and chaotic behavior has been studied and a control method has been proposed. This bioreactor shows oscillations for some special values of its parameters. The system dynamic is chaotic when a forced perturbation on the feed concentration is imposed. Dynamic behavior of this oscillatory and chaotic reactor has been illustrated. The main objective is control of product concentration. To do this, first system control is considered by proposing several control strategies for SISO case, then system in MIMO case is studied for achieving a globally controllable system. In SISO case, the performances of controllers are compared based on an objective... 

The goal of this project is finding an appropriate method for controlling four different bioreactors with unknown dynamics. At first, an introduction to bioreactor dynamic hase been presented, then their nonlinear behavior has been discussed. In the following, four output control systems using adaptive neural network have been designed separately for four different dynamics. The applied control method has been adapted from a method of references with some changes. Performances of designed controllers in set point tracking, load rejection and model mismatch have been evaluated using simulation. In these studies, input saturation has been considered in simulations but it is not existed in... 

Chaotic behavior takes place in different physical systems such as chemical reactors. In this thesis, dynamical behavior of chemical reactors in which polymerization or series reactions take place has been considered. It has been shown that these reactors have chaotic dynamics under special condition. Two reactors of the second type (with series reactions) for cases of known and unknown parameters have been synchronized by a control method and stability of the proposed scheme has been established by the Lyapunov stability theorem. Simulation results show the effectiveness of proposed method. Since concentration measurement is difficult and expensive, an observer has been used for... 

Controlling the nonlinear processes is very important in industry. In this thesis, model predictive control is considered as a nonlinear control strategy and two nonlinear models, namely wiener and Hammerstein models are used and their identification methods are described. State-space model is also considered and closed-loop stability has been studied. Another strategy for controlling the nonlinear process is global linearization control. Some concepts and related theorems for this strategy are stated. PID controller is used as a linear controller for this strategy. In this model for estimating the state and load, two nonlinear observers are used. Stability analysis of output feedback... 

In this thesis, a chaotic chemical process has been studied and a control method has been proposed. To do this, a reactor in which two autocatalytic reactions take place in parallel has been modeled. The catalyst decay has been considered as a separate reaction. The reactor dynamic is chaotic for a set of parameter values. In this thesis, dynamic behavior of this chaotic reactor has been analyzed. The main objective is to control the product concentration and a state feedback controller based on the process linearized model has been proposed. The suggested controller possesses integral action on desired concentration to eliminate control offset. Since concentration measurement is difficult... 

Continous blood glucose control has great importance for type 1 dyabetic patients. In this thesis, several types of controllers including: PI controller, model predictive controller base on state space model, linear model predictive controller base of linear input-output model and non-linear model predictive controller base of Hammerstein model have been used to regulate blood glucose of patients with type 1 diabetes. These models are identified using least squars method. Performance of these controllers is tested and the best one is introduced. For rejecting meal disturbances, a feedforward controller has been designed. Combination of feedback and feedforward controller would properly... 

In this study design of controller for a nonlinear system in the presence of state observer was investigated. First, nonlinear observers including non-adaptive and adaptive versions and their design procedures were studied. Then nonlinear adaptive controllers, based on sliding mode, feedback linearization and back-stepping techniques were implemented in the presence of observer dynamics. Two versions of adaptive law were proposed for unknown parameters identification in feedback linearization and sliding mode techniques. A new adaptive law was proposed to relax the restrictive condition that is used in adaptive observer design. The closed loop stability of back stepping technique was studied... 

Time delay systems may arise in practice for a variety of reasons, such as autonomous systems (without feedback control), and the delay is the result of an intrinsic property of the system. Sometimes the delay results from feedback control action, instead from the system itself; that is, due to the nature of the system, the feedback is delayed. Another type of delays of similar effects may be incurred due to delayed measurements. In both delayed control and delayed measurement, the delay is usually considered undesirable, which has the tendency to deteriorate the system performance or even destabilize the system.

In this thesis, three types of adaptive controller are proposed for... 

Methanol to Olefin (MTO) process is a part of the Methanol to Gasoline (MTG) production in a catalytic bed. Usually for this process, HZSM-5 or SAPO-n catalyst is used. In this research, dynamic modeling and simulation of the methanol to olefin catalytic reactor using HZSM-5 as the catalyst is done. The system is modeled based on the kinetic model for HZSM-5 presented by Castilla in 1999 [22]. Since the reaction is exothermic, taking use of a cooling system is essential. According to the high reactor temperature, a molten salt environment is used as the cooling media. In this cooling system, the molten salt absorbs heat of reaction from the reactor tubes and transfers it to a coil connected... 

Modeling and Control of Ethylene Oxide Reactor In this thesis, steady and dynamic modeling of an ethylene oxide fixed bed reactor has been studied and one dimensional pseudo homogeneous model was used for simulating the reactor. Kinetic parameters were obtained by minimizing an object function and using the genetic algorithm. A good agreement is observed between simulation and experimental results. In steady state condition, the influence of some parameters such as shell temperature, feed rate were investigated on the performance of the reactor. The heat of reaction is used to produce steam. A dynamic model for steam drum was also considered and used for control purpose. A PI controller was...